5 Least Sustainable Vegan (Plant-Based) Foods

5 Least Sustainable Vegan (Plant-Based) Foods

Quynh Nguyen

Read Time:11 Minutes


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Despite being generally better for the environment than meat and dairy, plant-based food is not always sustainable. Growing and selling vegetables, legumes, fruits, and nuts can greatly impact the environment and its ecosystems. When such an impact is not addressed or offset accordingly, a certain plant-based food becomes less and less sustainable. So we had to ask: What are the least sustainable vegan (plant-based) foods?

The least sustainable vegan foods are corn (because of fertilizer usage and monocropping), spinach (synthetic pesticides in non-organic farming), avocado (land and water usage), almond (water and fertilizer usage), and soybean (land usage).

Read on to find out what exactly makes these plant-based foods on our list so unsustainable. And also to find out what options you have to consume them more sustainably – just in case you’d still love to eat one of these or even everything on this list.

Here’s What Makes These Vegan (Plant-Based) Foods so Unsustainable

Unsustainability is often associated with a high carbon footprint, as carbon emission is the culprit for the current climate crisis. However, you can’t overlook other factors in the farming and selling processes. The usages of land, water, fertilizers, and pesticides all affect the ecosystems supporting a farm and all living things near and far. Together with carbon footprint, they indicate whether food is sustainable or not. 

  • Carbon footprint: Carbon footprint indicates the Greenhouse Gases (GHGs) emissions when making and distributing a product. The agriculture processes include clearing land, using heavy machinery, applying synthetic fertilizers, packaging, and transporting. These processes emit carbon dioxide, methane, and nitrous oxide, which are the GHGs responsible for climate change. 
  • Land usage: Land usage for some plant-based food accounts for the highest percentage of its carbon footprint. When forests, especially rainforests, are cut down to grow crops, their role as a carbon sink is diminished. Mass deforestation also poses an ecological danger as rainforests are hotspots for biodiversity. 
  • Pesticide usage: Pesticides sprayed on plants can leak into the surface and groundwater through run-off or leaching. That leads to harmful contamination for wildlife and humans depending on such water for food and drink. The residue of chemical pesticides can have detrimental impacts, such as causing cancer, hormone disruption, decreased cognitive function, or behavioral problems. 
  • Water footprint: Water footprint indicates the amount of freshwater needed for 1 lb of produce. Growing a thirsty crop on a large commercial scale can be a stress to the entire local ecosystems. 

Based on these four criteria, we pick out those five plant-based foods that are the least sustainable. Before we zoom into each one of them, it is essential to note that you can still buy (or grow) these plant-based foods sustainably. You only need to be aware of the problematic farming and consuming practices to make an informed decision.  

These Are the Least Sustainable Vegan (Plant-Based) Foods

Though vegetables, legumes, nuts, and fruits generally have much lower carbon footprints than meat and dairy, the environmental impact varies among plant-based foods. Water, fertilizers, and pesticides used for growing corn, spinach, almond, and soybean have serious ecological consequences and make them less sustainable. Deforestation caused by avocado and soybean farms increases carbon emissions and decreases biodiversity. 

Plant-based foodsWhy are they so unsustainable
Corn High level of fertilizer usage in its widespread monocropping
SpinachUsage of synthetic pesticides in non-organic farming
AvocadoExtensive land and water usage
AlmondExtensive water and fertilizer usage
SoybeanExtensive land usage

Though it is possible to get sustainable corn, spinach, avocado, almond, and soybean, you need to understand the widespread environmental problems in these industries to avoid bad practices.


Corn: Monocropping With Heavy Fertilizer Inputs 

Corn’s monoculture production depends on artificial fertilizers and pesticides, which pose existential threats to both the environment and humans. 

What Makes Corn So Unsustainable 

Corn is one of the least sustainable plant-based foods because of the high level of fertilizer usage in its widespread monocropping. 

Large-scale corn-only farming practices lead to soil degradation. Because corn depletes nitrogen and other vital nutrients from the ground, farmers apply synthetic fertilizers like ammonia. However, the surplus application is difficult to avoid and leads to leaching or runoff, causing air pollution and water contamination. 

Synthetic fertilizer production emits carbon dioxide and methane while its application releases nitrous oxide. Methane and nitrous oxide are potent GHGs, many times (90 and 250) more than carbon dioxide in the short-time effect of trapping the heat, accelerating global warming.

How Could We Eat Corn More Sustainably 

Monoculture is not a problem when corn is growing organically. If possible, go for organic when you buy a corn-on-cob or a can of sweet corn. However, beware that the challenge is beyond those two products as corn is very versatile. Besides being food for humans and feed for animals, corn can be found in many other food categories from flour to syrup, oil, and beyond (think Dextrin).


Spinach: The Most Pesticide Residue Per Pound

Despite spinach’s excellent health properties (what made Popeye incredibly strong, right?), conventionally grown and sold spinach has a high level of pesticide contamination, potentially harmful to human health and the environment.  

What Makes Non-Organic Spinach So Unsustainable 

Spinach is one of the least sustainable plant-based foods because of the usage of synthetic pesticides in non-organic farming. 

According to data on samples collected by USDA, spinach contains more pesticide residue by weight than any other vegetables tested. Of 54 pesticide residues found on spinach by the USDA Pesticide Data Program, seven could cause cancers, 21 are suspected of disrupting hormones, 11 are toxic for human’s neuro systems, seven are developmental or reproductive toxins, and 20 could harm bees. 

Permethrin, whose residue was found in spinach samples, is banned in the EU as it is considered an agent that can cause some types of cancer. Several studies found the link between low levels of permethrin exposure and neurological effects (such as ADHD) in children. 

How Could We Eat Spinach More Sustainably 

Buy organic spinach if you can. If you don’t have access to organic spinach, make sure you wash it thoroughly before using it. Freezing or cooking spinach would reduce the pesticide residue, so It’s better to eat it cooked than raw.

Other Vegetables With Similar Problems Of Pesticide Usages 

Kale, collard green, mustard green are also among the least sustainable vegetables due to pesticide usage. A single sample of kale, collard and mustard greens, collected and tested by USDA, had up to 20 different pesticides. Some examples are found with the residue of DCPA, or Dacthal, banned in the EU as a possible human carcinogen. These vegetables are nutrient-rich, and when they are grown organically, the pesticide residue is not a problem. 


Avocado: High Demand Leading to Large Scale Deforestation 

The healthy avocado fruit has recently become very popular – perhaps “the vegetable” of many vegans and vegetarians. High in vitamins, potassium, and unsaturated (good) fat, avocado is good for your health, but the avocado farming and consumption practices are not so for the environment. 

What Makes Avocados So Unsustainable 

Avocado is one of the least sustainable plant-based foods because of its extensive land and water usage. 

Avocados only grow natively in sub-tropical and tropical forests in places like Mexico. As the demand for avocado rises globally, more and more diverse forests have been cut down for this profitable crop. 

Without proper environmental regulations, widespread deforestation brings ecological challenges. Cutting down trees and tilting the ground for farming releases many GHGs and takes away the carbon-sink role of forests. Such deforestation also decreases biodiversity as those lost subtropical and tropical dry forests were also home to various fauna and flora. 

For large-scale commercial avocado farms in regions with a dry summer, their water usage could potentially be another environmental problem. As avocado is native to growing in a hot, moist climate, its shallow roots are poor at searching out water. When grown in California and Southern Spain, they demand heavy irrigation during the dry season and stress local surface and groundwater sources.

How Could We Eat Avocados More Sustainably 

The main reason for avocado being sustainable are the unusually high demand for the fruit from many regions where avocado doesn’t grow natively and the lack of regulations. The solution would be to consume it less frequently and opt for avocados that are organic, non GMO, and certified as sustainable


Almond: Intensive Farming Practices Damaging Local Ecosystems

Almonds – fruits of the almond tree – are consumed as whole nuts and ground meal or as an alternative to dairy. Almond has healthy fats, fiber, protein, magnesium and vitamin E, making it a nutritious plant-based food. California produces more than 80% of the world’s almond supply, and such a high concentration of intensive almond farming causes a series of ecological problems.

What Makes Almonds So Unsustainable 

Almond is one of the least sustainable plant-based food because of its extensive water and fertilizer usage. 

Together with cashew nuts and walnuts, almonds are amongst the most water-intensive large-scale crops on the planet. 963 gallons of water is needed to produce 1 pound of almonds with shell. The number is double for shelled or peeled almonds (about seven times more than the number for avocado or soybean). As most almonds farmed in California when the summer sees increasingly less rainfall, the crop water demand leads to depletion of groundwater reserves, worsening the state water crisis. 

The high value of the almond crop leads to farmers giving up other crops like citrus, which support relatively higher biodiversity. Almond monoculture depends on high inputs of fertilizers and pesticides. Synthetic fertilizers increase the nut’s carbon footprint while pesticides potentially contaminate surrounding air and water sources and harm bees. During the pollination period, bee colonies are trucked all over California, disrupting their natural living and exposing them to toxins and diseases. 

How Could We Eat Almonds More Sustainably 

Buy certified organic almonds as they are grown without artificial pesticides, which makes them safer for bees. It’s also worth considering other non-dairy alternatives, such as oat milk which has a smaller water footprint. 


Soybean: Deforestation Accelerating Climate Change

Soybean is a legume that provides vegetable protein to millions of people and animals. As it is an essential vegetable crop, the destruction in places like the Amazon in Brazil causes great concerns. 

What Makes Soybeans So Unsustainable 

Soybean is one of the least sustainable plant-based foods because of its extensive land usage. There is an increasing concern about Brazil’s soy production and the destruction of the Amazon and its ecosystems. Also, only 6% of soya is consumed by humans, while animal feed takes up the rest. It will be a more efficient use of the land if more soya is grown to feed humans. 

Soy production is similar to corn production in their monocropping culture. It depends heavily on fertilizers and pesticides, which cause a series of ecological issues. 

How Could We Eat Soybeans More Sustainably 

When you buy soy products, such as tofu or soy milk, opt for organic and sustainably-grown crops if possible. Avoid soybeans with a Brazilian origin, especially if they don’t have any sustainability certificates. 

How Does the Environmental Impact of Your Vegan (Plant-Based) Foods Compare to Other Foods 

Though some plant-based foods are less sustainable than others, plants are the most sustainable diet as a group. Using resources (like water, fertilizers, fossil fuel) to grow plants like soy or corn to feed humans would be a lot more efficient than feeding animals to produce meat. A chicken consumes 2 to 5 times the amount of feed to make such an amount of meat. The ratios for pigs and cows are even higher (up to 9 and 25 times, respectively). 

Regarding carbon footprint, CO2 emissions of most plant-based products are as much as 10 to 50 times lower than most animal-based products.

Illustration of environmental impact of food by life-cycle stage
Our World in Data: Food greenhouse gas emissions across the supply chain

How Can You Reduce the Environmental Impact of the Vegan (Plant-Based) Foods You Eat  

In general, eating vegetables, legumes, nuts, and fruits is better for the planet as growing plants – especially to harvest leaves as vegetables – have a low carbon footprint and require less natural resources than rearing cattle for meat and dairy. A diet containing mostly vegetables is also considered better for your health.

However, not all plant-based foods are equally sustainable, and the impact of growing and eating one vegetable varies widely according to the farming location and practices. Here are some rules of thumb for sustainable vegetarian and vegan diets. 

Consume in Moderation

An Italian study found two vegans whose diets had a significantly higher carbon footprint than many meat-eaters. The reason is their almost exclusive fruit-eating diet. The high water footprint and carbon footprint of the large, perishable fruits that make up their diet in large quantities make it unsustainable. Everything in moderation is a much better approach. 

For the avocado and almond of this list, the high demand worldwide encourages unsustainable practices in some growing areas. Suppose you and I consume less of these vegetables. In that case, the decrease in demand and price will take away the incentives for deforestation and large-scale monocropping, and intensive use of fertilizers and pesticides to increase yield. 

Avoid Air-Freighted, Out-Of-Season Vegetables and Fruits

One study found asparagus having an eight times higher carbon footprint than avocado because the perishable vegetable requires air travel to reach markets where they don’t grow or are out of season. The same principle applies to soft fruits like berries or bell peppers. 

Though it might be difficult to find out which vegetables are flown and which are trucked to your city, here are some other products that frequently transported by planes to the US: 

  • bell peppers (from the Netherlands), 
  • blackberries (from Chile), 
  • blueberries (from Chile, New Zealand, and Argentina), 
  • cherries (from Chile)
  • raspberries (Chile)

Choose Vegetables with Sustainable Certificates 

Certificates such as Rainforest Alliance and Carbon Neutral Certification indicating the compliance of sustainable farming practices. For example, Rainforest Alliance Certification on a bar of chocolate indicates that the production of such chocolate meets comprehensive standards that protect the environment. It would be a more sustainable option. 

4 Leading Reasons Why Growing Some Vegan (Plant-Based) Foods Has Become Unsustainable

Heavy Use of Agricultural Chemicals

Many of today’s leading agricultural chemicals are harmful not only to people but also to the environment. Pesticides, herbicides, and even some fertilizer products put toxins into the soil, which poisons the microorganisms. Similar to our immune system, these microorganisms play a critical role by destroying bacteria to maintain the soil’s health. 

These chemicals also hurt wildlife, intoxicate pollinators, and run off into nearby waterways, polluting rivers, wetlands, and surrounding land areas. 

Growing and Producing GMO Foods

Genetically Modified Organisms or GMOs are often created with the purpose to overcome some obstacles. In agriculture, GMO crops and seeds often are made to withstand a particular pesticide to which it has grown tolerant. 

Yet, the ironic problem that accompanied this solution is that GMO crops have generated a significant increase in farming practices utilizing agricultural chemicals. GMO crops must have pesticides and the like applied directly to the crop–a method most susceptible to widespread pollution.

Case and point: There have been multiple crop-contamination issues found, where the chemicals from GMO crop fields were found contaminating the non-GMO crop fields nearby. Chemicals were also found in local water and soil systems. 

Increased Use of “Crops Only” and “Animals Only” Farms

Over the last fifty years, with a rationale claiming “efficiency,” modern agriculture practices have segregated farming systems into specializations of monoculture, variegated-vegetable, or livestock farms. More often than not, this separation has led to the consolidation of commodities and their production. 

Indeed, there has been a harmonious coexistence between crops and animals seen throughout the world’s history, and we see it still today in hundreds of millions of small family farms. Livestock contributes to waste management and provides essential fertilizer. Cattle can be used to pull plows, which saves on CO2 emissions from farming equipment. In turn, crops provide the farm animals with a critical source of feed.

Monoculture Crop Farms

Monoculture cropping is the farming practice that cultivates a single crop in mass quantities. It can have favorable effects on yield and efficiency, but monoculture cropping often comes with environmental and social concerns. For one, this practice is contributing heavily to deforestation. Also, soil structure is being destroyed by the widespread use of heavy machinery. Not to mention the heavy amounts of agricultural chemicals being used.

Final Thoughts

A diet consisting mainly of vegetables, legumes, nuts, and fruits is generally much better for the planet and our health. However, not all plant-based foods are equally green. Though some problems could come down to impropriate environmental regulations, many lead back to the way we consume food. The demand for a particular food in an excess amount or out of season encourages practices driven by profits rather than with the ecosystems in mind.

While it takes a lot to change regulations regarding deforestation or monoculture, it is easy to consume less or avoid air-freighted out-of-season food. So think twice before you pick up the next avocado.

Stay impactful,


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